The present invention relates, in general, to panel wall systems, and more particularly to a system providing for flexibility in the installation of doors, windows, and accessories in the panel wall system, while maintaining the integrity of a clean room environment.
Panel wall systems are quite widely used in a variety of applications. Normally they are used as space dividers inside a larger structure. Applications include such diverse arenas as office dividers and semiconductor device fabrication clean rooms. It is this latter application, wherein the density of particulates in the atmosphere is strictly controlled, to which the present invention applies directly. The invention, however, can be easily adapted to other areas.
A typical wall panel system for a clean room is made with multiple wall sections. The sections are mounted in tracks affixed to the ceiling and floor of the building, and connected together by a system of battens. A front batten, normally relatively smooth, is placed on the front side (or inside) of the panels along the joint between two panels. The back of the front batten has two parallel flanges running the length of the batten. The flanges are spaced closely so that a screw will fit tightly between them. The flanges are then grooved such that the ridges act somewhat like the threads of a nut, enabling the front batten to hold a screw securely. A rear batten is then placed along the joint on the back side (or outside) of the panels. Screws are passed through holes in the rear batten and into the flanges on the back of the front batten, then tightened so as to hold the two panel sections together securely. In this way an entire system of walls can be built. Passage through the walls thus built is through door panels mounted between wall panels. Special factory-built door jamb assemblies allow interface with the standard front and rear battens. A transom is mounted above the door, filling the space left between wall panels above the door.
In the past, the installation of windows, doors, and other accessories introduced numerous ledges and other complex surfaces which could act as collectors of particulate matter. This tended to compromise the integrity of the clean room to an extent. For example, doors were mounted on pivot hinges which extended slightly into the room. The bottom plate of the pivot hinge could collect dust and interfere with clean room housekeeping. The use of butt hinges had the disadvantage that the weight of the door was supported only by the screws which held the hinges. The screws thus tended to pull out of the door jamb.
Windows of a fixed size were mounted into wall panels at the factory. A window installation that could be modified on site was introduced, but required the use of numerous fittings to frame the window. The frame was held in place by the same battens as used by the wall panels. The design of the frame created a ledge inside the clean room which could collect particulates. The installation process itself was complicated by the need to hold the front battens in place while affixing the rear battens, requiring two or more people to mount a window frame assembly.
The inflexibility of the system became apparent when it became necessary to make changes to the panel wall installation, or to add accessories to the clean room. Smaller accessories, such as a clean room telephone, were difficult to adapt to the panel wall system at all. Larger accessories, such as etchers, implanters, etc., that have openings located in the clean room, but are located substantially within maintenance bays, presented a particular challenge, requiring expensive precise manufacturing of custom wall panels.